{"id":"CVE-2026-120636","kind":"vulnerability","aliases":["CVE-2026-120636"],"related":[],"title":"Perl CGI: crafted REQUEST_URI builds redirects to other hosts","description":"CGI versions before 5.00 for Perl allow open redirects and script injection via URLs built from REQUEST_URI in url and start_form.\n\nurl(-absolute=>1), url(-relative=>1) and the default start_form action are built from the client-supplied REQUEST_URI without validation. The result can be protocol-relative (//evil.example), absolute-form (http://evil.example/) or contain backslashes, and url(-relative=>1) can return a javascript: URL. Links and form posts built from these URLs can go to another host.","summary":"The Perl CGI module builds URLs for links and forms from the client-supplied REQUEST_URI without validation. An attacker can make those links and form posts point to another host, or inject a javascript: URL.","severity":"medium","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["cgi.pm","package","perl","web-apps"],"not_affected_if":["cgi-not-used","version-5.00-or-later"],"how_to_check":"- Check the installed CGI module version with `perl -MCGI -e 'print $CGI::VERSION'`.\n- Search application code for `url(-absolute=>1)`, `url(-relative=>1)` and `start_form` calls.","fix":"- CGI for Perl: upgrade to `5.00` or later.","status":"open","published_at":"2026-11-04T00:17:24+00:00","first_seen_at":"2026-11-04T00:46:16+00:00","triaged_at":"2026-11-04T00:48:23+00:00","updated_at":"2026-11-04T00:48:23+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-11-04T00:48:23Z","model":"claude-haiku-5-5","output":{"fix":"- CGI for Perl: upgrade to `5.00` or later.","reach":"internet","title":"Perl CGI: crafted REQUEST_URI builds redirects to other hosts","impact":"medium","summary":"The Perl CGI module builds URLs for links and forms from the client-supplied REQUEST_URI without validation. An attacker can make those links and form posts point to another host, or inject a javascript: URL.","audience":"developers","category":"package","nicknames":[],"who_cares":["perl","cgi.pm","web-apps"],"confidence":0.6,"fix_status":"available","needs_auth":"no","worst_case":"users are redirected to other hosts or javascript runs in pages","analyst_note":"","how_to_check":"- Check the installed CGI module version with `perl -MCGI -e 'print $CGI::VERSION'`.\n- Search application code for `url(-absolute=>1)`, `url(-relative=>1)` and `start_form` calls.","plain_action":"","needs_analyst":false,"not_affected_if":["cgi-not-used","version-5.00-or-later"],"who_is_affected":"Web applications that use the Perl CGI module and build links or forms with url(-absolute=>1), url(-relative=>1) or the default start_form action are exposed. Applications that do not use CGI.pm, or that use it without these URL helpers, are less exposed; the sources do not say how the flaw is triggered beyond these calls.","user_interaction":"yes","needs_special_setup":"no","severity_if_unknown":"medium"},"cost_usd":0.001029,"input_tokens":4203,"output_tokens":1217,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-120636':13A,16A '-2026':12A,15A '/)':119C '/evil.example':113C '1':85C,88C,126C '5.00':63C 'absolut':84C,115C 'absolute-form':114C 'action':94C 'allow':66C 'anoth':53B,143C 'app':22B 'attack':43B 'backslash':122C 'build':6A,27B 'built':74C,96C,136C 'cgi':2A,25B,60C 'cgi.pm':17B 'client':36B,100C 'client-suppli':35B,99C 'contain':121C 'craft':3A 'cve':11A,14A 'default':91C 'evil.example':118C 'evil.example/)':117C 'form':32B,49B,82C,93C,116C,134C 'go':141C 'host':10A,54B,144C 'inject':56B,71C 'javascript':58B,130C 'link':30B,47B,132C 'make':45B 'modul':26B 'open':67C 'packag':18B 'perl':1A,19B,24B,65C 'point':51B 'post':50B,135C 'protocol':111C 'protocol-rel':110C 'redirect':7A,68C 'relat':87C,112C,125C 'request':4A,38B,76C,102C 'result':107C 'return':128C 'script':70C 'start':81C,92C 'suppli':37B,101C 'uri':5A,39B,77C,103C 'url':28B,59B,73C,79C,83C,86C,124C,131C,139C 'valid':41B,105C 'version':61C 'via':72C 'web':21B 'web-app':20B 'without':40B,104C","nicknames":[],"mitigations":[],"who_affected":"Web applications that use the Perl CGI module and build links or forms with url(-absolute=>1), url(-relative=>1) or the default start_form action are exposed. Applications that do not use CGI.pm, or that use it without these URL helpers, are less exposed; the sources do not say how the flaw is triggered beyond these calls.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"developers","plain_action":null,"pkeys":[],"ptokens":[],"labels":["cgipm","medium","package","perl","webapps"],"campaign_type":null,"first_public_at":"2026-11-04T00:17:24+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-120636","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-120636","severity":null,"published_at":"2026-11-04T00:17:24+00:00","modified_at":"2026-11-04T00:17:24+00:00","first_seen_at":"2026-11-04T00:46:16+00:00","fetched_at":"2026-11-04T00:46:16+00:00","note":null}],"documents":[{"id":62115,"url":"https://github.com/leejo/CGI.pm/commit/9405ef3909ee94991a3474167aa53b9051bd8765.patch","title":"Patch: github.com","kind":"other","source":"nvd","publisher":"vendor","text":null,"published_at":null,"relation":"fix","confidence":null,"note":"Patch: github.com"}],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}